REPORT ON CORALS—EXPLANATION OF PLATES. 221 
KE. Ectoderm here containing very few nematocysts but numerous nuclei. 
T, T. Tentacles in section. 
Fig. 2. Section transverse to the longitudinal axis of a large dactylozooid of Spora- 
dopora dichotoma. 
B. Body cavity of the zooid. 
L. Endoderm consisting of a double layer of large transparent nucleated 
cells with smaller cells on its inner aspect. 
M. Muscular layer and basement membrane showing a series of stout 
isolated fibres. 
E. Ectoderm. This forms a thick layer which contains numerous nuclei 
and developing nematocysts, and at its outer surface is protected 
by a continuous layer, one cell deep, of nematocysts of the 
smaller form. 
Fig. 3. Section parallel to the surface of the soft tissues of Sporadopora dichotoma 
taken at a very shght depth just beneath the superficial layer of the 
ectoderm. The soft structures about the mouths of the sacs of a 
gastrozooid and a contiguous dactylozooid are shown, and the radiate 
arrangement of the coenosarcal tubes around the sac openings. 
GZ. Lumen of the upper part of the sac of a gastrozooid. 
RM. Wall of the sac contaiming radially disposed fusiform muscular 
elements which are prolonged outwards on to the radial offsets of 
the coenosarc. The wall of the sac is lined internally by small 
rounded cells. 
R, R. Radially disposed offsets of the coenosarcal meshwork which pass 
inwards to joi the outer surface of the sac all round. 
A, A. Ships of fine transparent membrane containing nuclei attached to 
the radial offsets. 
X, X. Inter-radial spaces. 
DZ. Lumen of the sac of a dactylozooid with somewhat similar 
arrangement to that in the case of the gastrozooid. 
N, N. Nematophores. Closely packed batteries of the larger form of 
nematocysts, which are here seen in transverse section. 
Fig. 4. Tentacle of a gastrozooid of Sporadopora dichotoma, from a sketch made of 
the animal in the fresh condition. 
K. Elongate knob-like tip of the tentacle thickly beset with nematocysts 
of the smaller form. 
E. Ectoderm. 
Tr. “ Apparent septa.” 
C. Axial cavity of the tentacle. 
